Device physics of thin-film polycrystalline cells and modules. Annual subcontract report, December 6, 1994--December 5, 1995
- Colorado State Univ., Fort Collins, CO (United States)
This report describes the work on a number of projects carried out at both the cell and the module level during the past year. We investigated the effects of CdS thickness in collaboration with six CdTe cell-fabrication laboratories; there appears to be a critical thickness, between 500 and 1000 {Angstrom} depending on fabrication process, below which junction quality is degraded. Our experimental and modeling project showed that conduction-band offsets less than about 0.3 eV have little effect on the performance of a CuInSe{sub 2} (CIS) or CdTe cell under the traditional assumption that the absorber material accounts for most of the depletion region. The work in several other cell projects included the role of Ga distribution in Cu{sub 1-x}Ga{sub x}Se{sub 2} (CIGS) cells, changes that occur in some cells over time, optical characterization of commonly used CdTe substrates and front contacts, and comparative characterization of CIGS cells where identical absorbers were combined with variations in window fabrication. Our work on the primary module-characterization project developed the successful use of chopping-frequency variation in a scanning beam to separate photocurrent and shunting problems affecting individual cells of an encapsulated module. Other module projects included modifications in analysis required by the typical module-cell geometry, the practical effect of nonuniformities in light intensity or cell temperature, and the advantages and pitfalls of forward bias across a module during a light scan.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC36-83CH10093
- OSTI ID:
- 285451
- Report Number(s):
- NREL/TP-451-21586; ON: DE96013077; TRN: 96:005064
- Resource Relation:
- Other Information: PBD: Aug 1996
- Country of Publication:
- United States
- Language:
- English
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